Electrode system



April 28, 1936. w c VAN GEEL 1 2,38,616

ELECTRODE SYSTEM Filed June 14, 1952 NVENTOR WILLEM CHPJ5TAAN VAN GEELPatented Apr. 28, 1936 UNITED STATES PATENT OFFICE Delaware ApplicationJune 14, 1932, Serial No. 617,174

2 Claims.

The present invehtion relates to en electrode system in which at leastone of the electrodes consists at least partly of one of the metals ofthe first sub group of the fourth principal group of the periodic systemof the elements whereas the other electrode together with a supplyconductor is constituted by an electrolytically conducting substance.Such electrode systems are inter alla used as condensers.

The metals of the first sub group of the fourth principal group haveproved to be particularly adapted for this purpose which is evidentiydue to the great uniformity and stability of the oxide layer formed onthe electrodes and serving as an intermediate layer, by which thecurrent is blocked in one directlon. Owing to the proper nature of theoxide layer it may be rendered very thin without losing the blockingproperties. Due to this extremely thin layer it is possible, forinstance, to establish a. condenser having a very large capacity perunit of area.

It has been found that the manui'actureof such electrode systems forhigh tensions is attended with difiiculties when using the usualelectrolytically conducting materials. When exceeding the admissibletension which has often a value between and 250 volts, the oxide layerassumes a grey colour, while the current in the blocking directionincreases, so that the system becomes unsuitable for practical purposes.Only as long as the tension remains below 100 volts is it possible tokeep this current small, for in stance, below 0.01 ma.

When using other metals not belonging to the first sub group of thefourth principal group, for instance, aluminium, it has already beensuggested to dissolve the electrolyte in an alcohol for instance,glycerin and aluminium condensers, for instance, of this type arealready known. For this purpose alcohols were used containing a certainpercentage of water.

However, it has been found, that solutions in such alcohols are notadapted without additional means also for the metals of the first subgroup of the fourth principal group, since also in this case the currentpassing in the blocking direction highly increases for high tensons.

By electrolyte is to be understood in the present case a material whichin a suitable solution conducts the current electrolytically.

According to the invention the above difiiculties are avoided by using asolution of an electrolyte, in particular in an alcohol, for instance,glycerin which is entirely ree trom water.

When using such a solution it is possible to Germany June 26, 1931construct an electrode system by which the current is blocked in onedirection even at tensions of 600 volts and higher and which has a verylong lie. In addition the oxide layer can be kept very thin so that itis possible to obtain 5 a condenser having a large capacity and in whicha very week current passes in the blocking drection.

An electrolytic condenser incorporating the features of the invention isshown, by way of 10 example, in the drawing wherein Fig. 1 illustratesdiagrammatically a section through a preferred embodiment of theinvention and Fig. 2 is an end view of the device shown in Fig. 1 alongthe lines 11-11. In said figure, I is a coppervessel within which isarranged an electrode 2 consisting of a zlrconium band which is ro1ledup and whose successive windings are properly spaced apart by profiledcelluloid bands 3, said vessel being filled with a soluton 4 consistingof glycerin and primary potassium phosphate (KH2PO4) [50 gr. ofelectrolyte (KH2PO4) to the litre of solvent (glycerin) The electrode 2and the spacing bands 3 are supported on a base 5 which is suitablyplaced in the bottom of the container The base 5 acts to insulate theelectrode 2 from the container I. It should be noted that the support 5is provided with suitable apertures in order to permit the electrolytesolution to circulate ireely. A cover 8 is provided to seal theelectrolyte within the container. The two terminals 6 and 'I provde thenecessary external connections for the condenser.

The zirconium forms one of the electrodes whereas the solution togetherwith the vessel wall 35 consisting of copper constitutes the otherelectrode. Such a condenser may be used for smoothing direct current. Ata tension of 500 volts set up between the electrodes the current passingin the blocking direction is 0.02 ma. per microfarad.

Another suitable combination is glycerin and anhydrous phosphoric acid.It is also possible to use glycerin together with alum and citric acid,but in this case the solution must first of 45 all be boiled for sometime, so as to remove the water (crystal water of the alum). Speciflcexamples of the alum used are as follows:

K2SO4.A12 (S01) 3.24H20,

50 or else KA1(SO 2.12H20.

At any rate care must be taken that no water is present in the solution.

A condenser of the type referred to mayalso be 55 used for alternatingcurrent when piacing two electrodes (coated with an oxide layer)conslsting of zirconium, titanium, hafnium or thorium in the electroiytesolutionand i! each of them be connected with one pole.

11' the oxidation is eflected betere the electrode system is put intoservice as a condenser or a ree tifler, it is not always necessary thatthe oxidation occurs in the electroiyte solution in which the eiectrodesare eventually arranged.

'Ihe metais may be oxidized in soiutions of phosphoric acid in glycerin01 of ca.ustic alkaii or potash in ethyl alcohol, and in this case lessattention need be paid to the complete txeedom of wnter. As a. rule theoxidation is etfected a.t temperatures naar 100 C. tor instance, ingiycerin at 150 C. and in ethyi u.icohoi at 78 C.

Wint we claim is:

1. An eiectrolytic oell eomprislng a copper vessel a.cting as oneelectrode of the ceil, a. second electrode tot the cel1 comprising a.zirconium band rolled up and arranged so tha.t the successive windingstheregt are spaced, said second electrode being immersed within thecopper vessel in a. soiution consisting of glycerin a.nd primarypotassium phosphate in the approximate proportion of fifty grains ofpota.ssium phosphnte to the liter 01' glycerin.

2. An electrolytic condensor comprising a copper vessel acting as oneelcctrode thereot, a. second electrode 101 the condenser consisting ofa. spira1ly wound zirconium band provided with means intersposed betweenthe successive winding: so as to space the adja.cent windings. saidzirconium band being inserteci within said vessel. means 101insulatingiy supporting the band within the ven se], sa.id vessei beingfllled with a solution including glycerin and primary potassiumphospha.te in the approximate proportion of titty gxains of pota.ssiumphosphate to the liter 0! giycerin.

WILLEM CHRISTIAN v1m GEEL. JAN HENDRIK n! BOER.

